The present invention relates to a control system for collectively supervising a plurality of copiers or similar image forming apparatuses connected to a control device by communication lines with or without the intermediary of communication control units.
In a control system for the above application, copiers or similar image forming apparatuses are connected to a control device located at a service station by telephone lines or similar communication lines, as disclosed in, for example, Japanese Patent Laid-Open Publication Nos. 257155/1990, 259666/1990, and 196053/1991. By collectively controlling the remote image forming apparatuses by the single control device or host machine, it is possible to totalize the conditions in which each apparatus is used and to use the supervisory data for the maintenance of the apparatus. The conditions in which the image forming apparatus is used include the number of copies produced. On the other hand, the contents of maintenance include an automatic call origination to the control device resulted from the self-diagnosis of the image forming apparatus, and the adjustment of various sections of the apparatus executed by an access from the control device. These data can even be sent to, for example, the service station as image data implemented by a facsimile function. In the event of addition or version-up of a program, each image forming apparatus may receive the program from the control device or host machine and writes it therein, or at the time of maintenance the host may send guide data indicative of an operation procedure to the image forming apparatus in matching relation to the operating condition of the apparatus, as also proposed in the past.
Japanese Patent Laid-Open Publication No. 64770/1991, for example, teaches a control system in which a transmitting device is interposed between the communication line and the control device and selectively operable in a communication mode or in another mode. When the control device sends a data send request to a copier, the transmitting device operates in the communication mode only if the copier is not reproducing a document.
Further, assume that the line is busy when an error, for example, is to be sent from the copier to the control device. Then, data representative of the error is held until the line being monitored becomes ready. In case of emergency, a communication under way is forcibly ended by a relay circuit so as to send the emergency to the control device. Moreover, a particular time zone is allocated to each of the checking of the copier and the transmission of data to the host: the latter is effected in a time zone in which the line is not frequently occupied.
It is a common practice with modern copiers to accurately adjust data for image formation copier by copier at the time of shipment, so that each copier may produce attractive images from the beginning when installed at the user's station. Since the data generated at the time of shipment are stored copier by copier, a serviceman can readily readjust the copier by referencing the data in the event of an error or defective image, when data stored in the copier are destroyed, or at the time of replacement of a developer or a photoconductive element. This reduces the load on the serviceman and allows the copier to recover in a short period of time.
When the developer or the photoconductive element is replaced, it is sometimes desirable to restore all the data of the copier to their initial conditions, rather than to readjust the data one by one. In the light of this, a copier having a memory clearing function has also been proposed.
However, the problem with the conventional control system is that the serviceman has to down-load the data of the copier from the control device or up-load the data of the copier to the control device. The up-loading and down-loading operations still pose a substantial load on the serviceman. Moreover, since the data cannot be supervised without resorting to manual operations, it is likely that the up-loading procedure is omitted by accident.
A copier with multiple functions available today allows various initial modes to be selectively set up to the user's taste when the power source of the copier is turned on. For example, an arrangement may be made such that while in the standard specifications the first sheet cassette is automatically selected out of a plurality of cassettes on the turn-on of the power source, the second sheet cassette can be selected on an operation panel. Also, a buzzer may be muted, as desired by the user. However, in the conventional control system, a serviceman has to set such conditions by manipulating the operation panel at the time of delivery. This increases the load on the serviceman as the number of functions increases.
The drawback with the copier of the type having a memory clearing function is that since the initial data stored in all the copiers are identical, the serviceman has to readjust necessary data at the cost of time. The serviceman may inquire the service station the initial data generated at the time of delivery or may operate the operation panel to read them out of the control device. Although this may reduce the adjustment time, the load on the serviceman is still heavy. Moreover, since the data cannot be supervised without resorting to manual operations, it is likely that the up-loading procedure is omitted by accident.
Assume the control system of the type setting up a communication mode only when the image forming apparatus is not forming an image, as mentioned earlier. Even with this type of system, it is likely that the data representative of adjusted image forming conditions are destroyed since the system allows the image forming apparatus to communicate with the control device by an interruption when the apparatus is automatically adjusting the image forming conditions. The automatic adjustment includes the adjustment of a lamp voltage for reducing the contamination of the background, i.e., automatic VL correction.
When a communication is held between the image forming apparatus and the control device in parallel with the automatic adjustment of image forming conditions, a CPU (Central Processing Unit) built in the apparatus is driven hard, lowering the processing speed. Although such a problem may be eliminated if the control method is complicated, this cannot be done unless the software is changed, resulting in an increase in cost.
Assume that the control device generates a communicatin request while the automatic adjustment of image forming conditions is under way, and priority is given to communication by interrupting the adjustment. Then, after the communication, the adjustment interrupted halfway has to be executed all over again. This forces the operator to await the end of the automatic adjustment, wasting additional several minutes. Further, if the image forming apparatus begins to communicate with the control device when a person intends to use the apparatus, the person has to wait until the communication ends.
Assume that the image forming apparatus communicates with the control device when user-oriented special modes are being set on the apparatus. Then, when data is rewritten by communication processing, the modes being set are sometimes invalidated. For example, when a data rewrite communication for cancelling an automatic sheet select mode is effected while a program mode (special mode) including an automatic sheet select mode is being entered, the mode being entered is invalidated due to the difference in sheet select mode. In such a case, the mode has to be set all over again after the communication, preventing the apparatus from being used just after the communication.
In the control system wherein a number of copiers or similar image forming apparatuses are connected to a control device located at, for example, a service station by communication control units or data terminals and telephone lines or similar communication lines, the communication control units usually associated with the image forming apparatuses each controls the communication with the control device. When the communicable condition of the image forming apparatus and communication control unit changes, e.g., when a change from a connected state to a disconnected state occurs, the apparatus detects an error, generates a serviceman call, and stops the operation. Although a change from the disconnected state to the connected state may occur while the operation of the apparatus is stopped, the apparatus does not become usable unless manipulated by a serviceman. This type of system, therefore, cannot adopt an expedient in response to a change in the connection condition of the apparatus and communication control unit, so that the operation efficiency available with the system is limited.